impl fmt::String for tuples

[milibopp]

This does not work:

println!("{}", ());

and neither does this with any tuple atm.

Or is this intentional?

[alexcrichton]

This is currently intentional, and I believe that @aturon will open an RFC soon about Show/String conventions, so stay tuned to the RFC repo!

[alexcrichton]

rust-lang/rfcs#565 (now opened)